Re: Fastest //e?

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4h8fe3$lpk@gaia.ns.utk.edu>,
Krishna Sadasivam  <kms@nestor.engr.utk.edu> wrote:
> 
> What is the fastest MHz speed of the 65c02?

At least 8 MHz, probably faster.

> I remember hearing that a 12 MHz microprocessor replacement (a la Zip
> Chip) was available.

Whoa!  You have a couple of concepts confused there.

A ZIP chip is more than just a faster microprocessor.  It also
contains some special hardware to interface the microprocessor to the
Apple at the original bus speed (1 MHz), handling synchronization as
required, and 8 KB of cache RAM for holding data read from memory.

The processor inside the ZIP is only able to run at its full speed
when accessing data that has already been cached.


Just putting a faster 65C02 into an Apple will not make the slightest
difference to the execution speed of the computer.  The CPU is
controlled by an external clock, which runs at 1.023 MHz (or
thereabouts), derived from a 14.31818 MHz clock which is also used to
provide all timing for the video circuitry.  You cannot change this
without totally screwing up the execution of the rest of the computer.


It might be possible to use a high-speed 65C02 on an accelerator card
such as TransWarp IIe, provided the card has been designed to allow
the processor speed to be increased (which I doubt).

> I also remember reading that the //e could be expanded up to 16 MEGs
> of RAM.  

Sort of.  In theory, a "slinky" RAM card (standard slot) can support
up to 16 MB of RAM.  I don't know if the RamFactor ever had an
expansion card which would allow this much.

Similarly, an auxiliary slot multi-bank card could theoretically
support up to 16 MB, but again I don't know of any expansion card
which provides this much

The largest I know of is a 2 MB expansion card for the RamFactor or
RamWorks, giving you 3 MB in total.

Nowadays it may be possible to use higher density chips to create a
larger expansion board.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand